Effects of annealing on the structural and surface properties of buried silicon oxide layers synthesized by the SIMOX process

Abstract

Silicon oxide (SiO2)-buried insulating layers were synthesized by separation by an implanted oxygen process using 140 keV (16O+) implantation into ⟨ 111⟩ single-crystal silicon at room temperature at low fluence levels ranging from 1.0×1016 to 7.0×1016 cm−2. The buried silicon oxide layers have been characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques before and after annealing at 1200 °C for 30 min in argon ambient. The FTIR spectra after annealing of the samples revealed an absorption band associated with one bending vibration in addition to the asymmetric stretching vibration of Si‒O bonds. The XRD spectra of as-implanted samples showed a decrease in the peak (111) intensity with an increase in the ion fluence. The peak intensity was found to increase for all the implanted samples on annealing. The XRD studies revealed the formation of silicon oxide (SiO2) at all ion fluences. The AFM image of the crystalline silicon showed a very smooth micrograph. However, the AFM micrograph of the annealed samples showed nano-hillock-like structures on the silicon surface.